Etjektace



A. l. McGEHEE FURNACE.

APPLICATION HLED JULY 5,1918.

lfil fi iU n Patented Gut. 21,1919.

ABNER JUDSON MOGEHEE, 0F JAGKs0lN, TENNESSEE.

summon.

Specification of Letters Patent.

Patented Oct. 21, 1919.

Application filed July 5, 1918. Serial No. 243,404.

To all whom it may concern:

Be it known that I, ABNER J. MoGnHnn, a citizen of the United States, and a resident of Jackson, in the county of Madison and State of Tennessee, have invented certain new and useful Improvements in Furnaces; and I do hereby declare the follow ing to be a full, clear, and exact descriptlon ofthe invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in furnaces or stoves and more particularly to a system embodying means for returning the smoke and gases to the fire chamber, one object of the invention being to provide a system of the character specified which will operate to effect great economy in the use of fuel and at the same time enhance the efficiency of the stove or furnace.

A' further object is to provide a construction which will avoid the intake of cold air to commingle with the smoke and gases leaving the fire chamber but will insure the heating of the incoming fresh air so that its mixture with the smoke and gases before the same enter the fire chamber will enhance the combustibility of such smoke and gases.

A further object is to provide, in a smoke and gas consuming furnace system, means whereby fresh air will be taken into the mixing chamber in a relatively dry condition and so as to avoid interference of weather conditions and variable wind pressure which always prevail outside of the boiler house or inclosure.

A further object is to so construct and arrange the various features of the system that the smoke, gases and air are allowed to be carried in their natural direction of movement until they are deflected downwardly to the fire chamber.

A further object is to so construct and arrange a system of the character specified, that the same may be readily and accurately controlled.

With these and other objects in view, the invention consists in certain novel features of construction and combinations of parts as hereinafter set forth and pointed out in the claims.

In the accompanying drawings; Figure 1 1s a view partly in elevation and partly in on the line 2-2 of Fig. 1; Fig. 3 is a view in section on the line 33 of Fig. 1, and Fig. 4: is a View showing a modification.

1 represents a steam boiler furnace and 2 the smoke flue or stack communicating with the smoke box thereof. In the form of the invention shown in Fig. 1, a partition 3 is located iii the lower portion of the stack so as to form two stack chambers 4i and 5 to receive products of combustion of the furvalve or damper 6. A pipe or flue 7 communicates at one end with the mixing chamber 5 near the upper end of the latter, and at its other end, said pipe or flue communicates with the furnace below the grate thereof, a damper 8 being provided in said pipe or flue, as shown in Fig. 1. A lateral pipe 9 communicates with the pipe 8 and the said pipe 9 is provided with discharge nozzles 9 which enter the fire chamber of the furnace so as to discharge over the fire in a manner to direct the flame rearwardly and prevent overheating of any one part of the boiler. v

An air pipe 10 passes through the stack chamber 4 so as to be heated by the hot products of combustion passing through said chamber and communicates with the lower portion of the mixing chamber 5. The air pipe extends from the stack clownwardly in close proximity to the boiler and the furnace so as to be heated by the same. The lower end of the air pipe is open and a damper 11 is provided in this pipe some distance above its lower end. A fan 12 is located just over the damper 11 so as to create a forced draft of fresh air through the pipe 10 and into the lower end of the mixing chamber 5. The damper 11 is so located that it may be operated to control the amount of fresh air forced through the pipe 10. The fan may be driven by an electric motor (not shown) or it may be driven from an engine supplied with steam from the boiler of the furnace.

For the purpose of utilizing the upthrust of the gases and hot air as the same escape up the stack through the chamber a and to enhance the inflow of the fresh air through the pipe 10, I provide a small air outlet in said air pipe at 10 controlled by a valve 10". The air, pipe may be larger than is necessary to supply the quantity of air required to be returned to the furnace and a portion of it may be allowed to escape from said pipe through the outlet 10 into the chamber 4 of the smoke stack and the suction upward of the gases rising in said stack chamber will act to draw out air from pipe 10 (said air escaping into chamber 4 from the air pipe) and thus act as an inspirator for the air flowing through the air pipe. This manner of causing a flow of fresh air may serve to augment thefunction of the fan and in some cases I may dispense with the use of the latter.

It is well known that excessive admission of cold air into the fire chamber of a furnace tends to hinder complete combustion and the economic use of fuel. The system which I have devised provides for the return of the smoke and gaseous products of combustion mixed with dry, hot, fresh air over and under the grate in order that the combustible products of partial combustion shall be consumed in the furnace When mixed with air already hot when it becomes intermixed with combustible gases, thus effectively saving the latter for use as fuel and saving the heat of the furnace otherwise wasted in raising the temperature of the air.

By providing an intake for fresh air in close proximity to the boiler, the air is not only preheated, but it will not be affected by moist weather conditions and variable wind pressure, as would be liable to occur if the air were taken from the outside of the furnace or boiler house or inclosure. I am therefore enabled to supply the needed quantity of fresh air under a constant pressure,'thus assuring regular results without being forced to resortconstantly to the adjusting of dampers to meet the requirements of economic combustion in the furnace.

It will also be observed that withmy improvements the air and gases are allowed to flow in their natural direction of movement until they are forced downwardly to the fire chamber of the furnace, thus greatly assisting the fan. When my improvements are applied to small stoves and furnaces, a sufficient circulation may be effected without the use of the force fan as the flow of the products of combustion through the stack chambers will tend to draw fresh air into the lower end of the chamber 5, but with large furnaces I prefer to employ the fan.

, It will be understood that when the'fire in the furnace is first started, the full draft of the stack may behad by opening the damper 6 at the upper end of the mixing chamber as indicated by dotted lines in Fi 1.

In the construction shown in Fig. 4 the mixing chamber within the stack is formed by means of a tube 13 located centrally within the lower portion of the stack so as to communicate with the smoke box of the furnace. This tube is provided at its lower end with a damper 14 and its upper end with a damper 15 which perform the same functions as the dampers 6' and 6 in the construction shown in Fi 1. In other respects, the arrangement shown in Fig. 4 is substantially the same in construction and mode of operation as the construction shown in Fig. 1.

Other changes might be made in the details of construction of my invention without departing from the spirit thereof or limiting its scope and hence I do not wish to restrict myself to the precise details herein set forth. 7 v

Having fully described my invention what I claim as new and desire to secure by Letters-Patent, is

1. The combination with a furnace and its smoke stack, of a mixing chamber within the smoke stack and adapted at its lower end to communicate with the furnace and at its upper end with the stack, means for closing the upper end of said mixing chamber, a pipe connecting the upper portion of said mixing chamber with the lower portion of the furnace, and an air inlet flue disposed in such proximity to the furnace as to be heated thereby, said flue communicating with the lower portion of the mixing chamber for discharging preheated air thereinto.

2. The combination with a furnace and its smoke stack, of a. mixing chamber, having an upper open end, located within the lower portion of the smoke stack and adapted at its lower end to communicate with the furnace, a da-mperfor closing the upper open end of said mixing chamber, a pipe connecting the 'upper portion of the mixing chamber with the lower portion of the furnace, and a fresh air inlet pipe located in proximity to the furnace whereby it will be heated, said air inlet pipe communicating with the lower portion of the mixing chamber in the stack, and means for controlling the flow of air through said inlet pipe.

3. The combination with a furnace and its smoke stack, of a mixing chamber within the smoke stack and adapted at its lower end to communicate with the furnace and at its upper'end to communicate with the stack, a damper at the upper end of said mixing chamber, afresh, air inlet pipe located in proximity to the furnace whereby it may be heated said inlet pipe communicating with the lower portion of the mixing chamber, a damper in said air pipe, a respecification in the presence of tWo subscribturn pipef rilommunicatilng Ilvvith ghe uppfir ing Witnesses.

ortiono t emixin 0 am er an Witht e urnace near the grite thereof, and a fan ABNER JUDSON MCGEHEE' 5 positioned to force air through said air Witnesses:

pipe. T. B. CARROLL, In testimony whereof, I have signed this CARL F. WARD.

copies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents, Washington, D. G. 

